D (letter)

D is the fourth letter of the Latin alphabet, used in Somali and many other languages. The uppercase form is "D", and the lowercase form is "d". In most languages, it represents a voiced alveolar or dental stop, for example the sound at the beginning of the word "dab" (fire).

The letter has a long history tracing back to early Semitic writing, and subsequently passed through Greek and Latin before reaching its present form. Its use extends beyond language; it also appears in mathematical notation, music, and numeral systems.

Historical origin

The letter is traced to the early Semitic symbol daleth, meaning "door". The Greeks developed from it the letter delta (Δ, δ). The Romans, by way of Etruscan, adopted a rounded form with one straight side, which became the modern D.

Sound

In Somali, D represents a voiced sound made with the tongue and teeth or upper ridge. There is also the digraph DH in Somali, which represents a different sound (retroflex), as in the word "dhagax" (stone). In other languages, D may represent various sounds depending on the phonological system.

Use as a symbol

In Roman numerals, D stands for 500. In certain musical systems, D is the name of a note. In mathematics, science, and technology, the letter is used for various symbols, such as mathematical variables or typographic marks.